MAcNLOPS for ZZ pair production at the LHC

We present an implementation of the MAcNLOPS matching prescription for pp→ ZZ p p → Z Z production in a MadGraph5_aMC@NLO + Pythia8 setup. Starting from a standard MC@NLO event sample, negative H H events are removed and compensated by a veto applied to the first shower emission of the S S events. The implementation is validated against MC@NLO for radiation-sensitive and inclusive diboson observables. Agreement is found up to a rather small power-suppressed contribution affecting the very low- pT p T region. The method removes all negative H H weights with negligible additional computational cost, while negative S S weights are left unchanged, showing that MAcNLOPS is a promising alternative to MC@NLO with a reduced fraction of negative weights.